Joe Biden on Wednesday addressed the elephant in the room of his 2024 re-election bid: the fact that he is already the oldest ever president and would be 86 when he stepped down if he wins.

The veteran Democrat rarely talks about his age.

But polls show it's a matter of overwhelming concern for voters -- and one his Republican opponent will weaponize.

At a press conference Wednesday, the day after the low-key launch of his campaign via video, the 80-year-old president said it was normal for people to ask questions.

He admitted he'd thought hard about the issue himself.

"I respect them taking a hard look at it. I'd take a hard look at it as well – I took a hard look at it before I decided to run," he said.

Biden, speaking alongside South Korean President Yoon Suk Yeol in the White House Rose Garden, said he was confident about what is likely to be a grueling election battle, all while working in one of the world's most demanding jobs.

"I feel good, I feel excited about the prospects," he said. "People are going to find out. They are going to see a race and they are going to judge whether I have it or don't have it."

Biden tried joking, saying "I can't even say I guess how old I am. I can't even say the number -- it doesn't register."

Trump's insults

Gentle jokes about how long he has been around -- serving as a senator for 36 years and vice president to the younger Barack Obama for eight -- are usually the only way Biden discusses the age question.

Voters, however, are not laughing.

An NBC News poll released last weekend found that 70 percent of Americans, including 51 percent of Democrats, believe he should not run in 2024. And 69 percent of all respondents who said he shouldn't run cited concerns over his age as a major or minor reason.

If re-elected, Biden would be 82 when he took office for a second term in January 2025. The previously oldest president was Ronald Reagan, who was 77 when he completed his second term in 1989.

Biden seems driven to keep going not just because that's what first term presidents always do but from a sense of historic mission to stop Donald Trump, whom he defeated in 2020, from coming back.

Trump is currently the overwhelming frontrunner for the Republican nomination, despite being the subject of multiple legal cases -- the latest hearing this week was on a rape allegation in a New York court -- and his role in trying to overturn the 2020 election.

When Biden challenged Trump in 2020, the Republican savaged him over his age, deriding him as "Sleepy Joe" and offering up crude insults about his mental state. The attack will certainly return, likely in new intensity, if Trump wins his party nomination.

Asked Wednesday if he considered himself the only person who could defeat Trump, Biden said: "I may not be the only one, but I know him well, and I know the danger he presents to our democracy and we've been down this road before."